Your LightBurn registration code by default is good for up to two computers. You should be able to use the same code on a second machine without any trouble.
If you need to license a third machine, typically Oz and crew will do that for you - send an email to support (at) lightburnsoftware.com with your license code and ask them if they’d allow a third seat on the license.
If you really don’t need to have the machine you mentioned licensed at all, you can go to the Help menu, choose License Management, then click Deactivate License. This will allow your code to be used on another computer.
Good luck. If you have any more LightBurn-specific questions, the folks at forum.lightburnsoftware.com are the experts and will be able to better answer any questions you have about the product.